"Perfected" version + add support for return key event

//Problem: user interaction doesn't provide desired results

//Solution: add interactivity so the user can manage daily tasks

//Interaction needed:

var taskInput = document.getElementById('new-task');

var addButton = document.getElementsByTagName('button')[0];
var editButton;
var deleteButton;

var incompleteTaskHolder = document.getElementById('incomplete-tasks');
var completedTaskHolder = document.getElementById('completed-tasks');

var createNewTaskElement = function(taskString) {

  var listItem = document.createElement('li');

  //add input (checkbox)
  var checkbox = document.createElement('input');
  checkbox.type = "checkbox";

  //label
  var label = document.createElement('label');
  label.innerText = taskString;

  //input (text) for editing
  var editInput = document.createElement('input');
  editInput.type = "text";

  //button .edit
  var editButton = document.createElement('button');
  editButton.className += " edit";
  editButton.innerText = "Edit";

  //button .delete
  var deleteButton = document.createElement('button');
  deleteButton.className += " delete";
  deleteButton.innerText = "Delete";

  //apppend all elements to document
  listItem.appendChild(checkbox);
  listItem.appendChild(label);
  listItem.appendChild(editInput);
  listItem.appendChild(editButton);
  listItem.appendChild(deleteButton);

  return listItem;
}

//add a task
var addTask = function() {
  console.log('Add task');
  console.log(taskInput.value);

  if(taskInput.value){
    //create news list item with the text from #new-task
    var listItem = createNewTaskElement(taskInput.value);

    //bind events to new task
     bindTaskEvents(listItem, taskCompleted);

    //append listItem to the incomplete list
    incompleteTaskHolder.appendChild(listItem);

    //clear input value
    taskInput.value = '';
  } else {
    alert("Please enter a task");
  }
}

//add a task by pressing enter on task input
var enterKeyPress = function(e, handler){
  if (e.which == 13 || e.keyCode == 13){
    console.log('You pressed the enter key!');
    handler(e);
  }
}

//edit a task
var editTask = function(e) {
  console.log('Edit task');

  var eventTarget = e.currentTarget;
  var listItem = eventTarget.parentNode;
  var label = listItem.querySelector('label');
  var editInput = listItem.querySelector('input[type=text]');
  var editButton = listItem.querySelector('button[class=edit]');

    //if the parent has class .editMode
  if(listItem.classList.contains('editMode')){
    //exit .editMode, switch to normal mode
    listItem.classList.remove('editMode');
    //update label text with input value (save task)
    label.innerText = editInput.value;
    //update edit button text
    editButton.innerText = 'Edit';
  } else {
    //enter .editMode, reveal edit input
    listItem.classList.add('editMode');
    //make input value the text from the label
    editInput.value = label.innerText;
    //update edit button text
    editButton.innerText = 'Save';
  }
}

//delete a task
var deleteTask = function() {
  console.log('Delete task');
  //remove the parent (li) from list (ul)
  var listItem = this.parentNode;
  var ul = listItem.parentNode;
  ul.removeChild(listItem);
}

//mark a task as complete
var taskCompleted = function(){
  console.log('Task completed');
  //append (move) task to the #completed-tasks
  var listItem = this.parentNode;  
  completedTaskHolder.appendChild(listItem);
  bindTaskEvents(listItem, taskIncomplete);
}

//mark a task as incomplete
var taskIncomplete = function() {
  console.log('Task incomplete');
  //append (move) task to the #incomplete-tasks
  var listItem = this.parentNode;  
  incompleteTaskHolder.appendChild(listItem);
  bindTaskEvents(listItem, taskCompleted);
}

var bindTaskEvents = function(taskListItem, checkBoxEventHandler){
  console.log('bind list items event');
  //select taskListItems children
   var checkbox = taskListItem.querySelector('input[type=checkbox]');
   var editButton = taskListItem.querySelector('button.edit');
   var editInput = taskListItem.querySelector('input[type=text]');
   var deleteButton = taskListItem.querySelector('button.delete');

  //bind editTaskt to edit button
    //when clicking on button
    editButton.addEventListener('click', editTask);
    editInput.addEventListener('keypress', function(e){
      enterKeyPress(e, editTask);
    });

  //bind deleteTask to delete button
    deleteButton.addEventListener('click', deleteTask);

  //bind checkBoxEventHandler to checkbox
    checkbox.onchange = checkBoxEventHandler;
};

//Add task event by clicking on button
addButton.addEventListener('click', addTask);

//Add task event by pressing Enter key
taskInput.addEventListener('keypress', function(e) {
  enterKeyPress(e, addTask);
});

var falsefunction = function(){
  console.log('false function');
}

addButton.addEventListener('click', falsefunction);

//Add events to items
//cycle over incompleteTaskHolder ul li items
    var incompleteChildren = incompleteTaskHolder.children;
    for (var i = 0; i < incompleteChildren.length; i++) {
      //bind events to children elements to mark tasks as completed (taskCompleted)
      bindTaskEvents(incompleteChildren[i], taskCompleted);
    }


//cycle over completedTaskHolder ul li items
    var completeChildren = completedTaskHolder.children;
    for (var i = 0; i < completeChildren.length; i++) {
      //bind events to children elements to mark tasks as completed (taskCompleted)
      bindTaskEvents(completeChildren[i], taskIncomplete);
    }